We recently brought you the story about drones being used by an animal rights group to spy on farmers. Well there's a range of other uses for these unmanned aerial vehicles that farmers are more likely to welcome.

While it's early days for these eyes in the sky, they're being used to assess crop health and productivity, spray hard-to-reach weeds, even round up dairy cattle.

Prue Adams has been delving into this brave, new world and brings you the latest on the drones that are coming.

PRUE ADAMS, REPORTER: Things have been warming up in the northern Victorian almond orchards. The trees are blooming, the bees buzzing. Situation normal for spring. Except for this.

Meet Shrimp, a ground-based robot designed to meander among the almonds collecting all sorts of interesting and useful data.

And Shrimp boasts an aerial partner, a hexacopter loaded with a camera.

ZHE XU, CENTRE FOR FIELD ROBOTICS: So we're flying an unmanned aerial vehicle, or a UAV, with a downward-pointing camera and that camera is capturing high-resolution images that provide a rather unique perspective on the trees. And we're going to be using that data to pick out individual - or clumps of flowers and hopefully that will become quite correlated with how many almonds form and the information that's being collected by the ground robots.

PRUE ADAMS: Zhe Xu is one part of a highly-qualified team hailing from the Australian Centre for Field Robotics based at Sydney University. It's a group that's taken robots, both land-based and aerial, out of the laboratory and into orchards, beef cattle properties, even dairies.

JAMES UNDERWOOD, CENTRE FOR FIELD ROBOTICS: It's absolutely fascinating. I mean, it's a really great use of, you know, state-of-the-art robotics and sensing technology. We've done a lot of work at the ACFR in different areas like mining and defence and so on, but agriculture I think is really starting to see the benefits of this technology flowing into that industry.

PRUE ADAMS: The ACFR's Professor Salah Sukkarieh has been with the centre since its beginning in the late 1990s and he's overseen considerable design changes. The term "drone", with its negative military connotation, is no longer favoured. The preferred term is "unmanned aerial vehicles", UAVs, or even "robotic aircraft".

While the aircraft attract a lot of interest, the information they record and analyse is really the main game.

SALAH SUKKARIEH, UNIVERSITY OF SYDNEY: 10 years ago, the interest would've been - the fascination would've been on the platform itself, but now that we can fly, now we can buy things off the shelf, where the interest is, is what type of sensors we can put on board and what can we do with that data? What does that data give us that's different from anything else that we can currently collect? And that's where predominantly a lot of that interest is now.

PRUE ADAMS: In 2009, with funding from Meat and Livestock Australia, the team at Sydney Uni developed an unmanned fixed-wing plane and took it out to a cattle property near Julia Creek in western Queensland. With a camera on board, the aim was to detect, map and later eradicate the woody weeds that invade these land holdings - large trees such as prickly acacia, parkinsonia and mesquite.

Nathan March, who at the time was the Weeds National Control Co-ordinator, says these pests cost rural industry upwards of $20 million a year.

NATHAN MARCH, WEEDS CONTROL CO-ORDINATOR: At a property level, these weeds can cost over $100,000 per property per annum where you've got larger, dense infestations and that's primarily from the lost productivity, lost cattle and sheep production.

PRUE ADAMS: The GPS co-ordinates of some of the weeds were verified on the ground and the aircraft uploaded with way points across the property, so it could develop its own flight path. While it flew autonomously, its speed, altitude, direction and power were all monitored from a land-based laptop.

OPERATOR: So this is the ground station where we operate the unmanned aircraft from. These numbers are all colour coded, where green is good, yellow is a warning and red is bad. Currently all the numbers are green, so that means the aircraft is happy and good.

PRUE ADAMS: Using an unmanned aircraft is considered safer and cheaper than collecting the data from a piloted craft, and the researchers say this plane could get into areas a bigger manned vehicle couldn't.

MITCH BRYSON, CENTRE FOR FIELD ROBOTICS: Because we're at a lower altitude, we can start to see things like the texture, shape, different colours and types of branches, and thus use these properties to distinguish between different types of plants.

PRUE ADAMS: The solid state drive was removed from the UAV at the end of the flight and the data passed through a set of algorithms that automatically stitched the required information together.

SALAH SUKKARIEH: But also these little colours that you see there is the algorithms now detecting what's a eucalyptus tree versus what's parkinsonia, mesquite, etc., so being able to classify the different vegetation.

PRUE ADAMS: Right. So each colour represents another type of tree.

SALAH SUKKARIEH: That's right. And also, the spot there is geo-referenced so we know its GPS co-ordinates because we've gone over and we've surveyed certain parts of the land and the UAV's flown over, so we know each and every spot where it is in GPS frame.

PRUE ADAMS: An unmanned helicopter would later drop granular herbicide on those geo-referenced weeds. It's a process the robotics researchers have also applied to the control of weeds along difficult-to-access waterways. And, they've even looked at mapping locust swarms using UVAs.

SALAH SUKKARIEH: So what we were able to do was mount appropriate sensors on the locusts themselves, so little retro-reflecting tape. And the UAV would fly over and it would take imagery.

From a research perspective, what they're interested in is how do they model swarms, and from an operational perspective, it's all about the control barriers that they want. What are the most appropriate control barriers and can they understand a little bit more about the process of when they hatch and then how long does it take to then form a swarm and how quickly does that swarm form and what shapes do they take on?

PRUE ADAMS: While there are enthusiasts trying to muster beef cattle with unmanned aircraft, this was the first time dairy cows had been herded by a sophisticated ground-based robot. Shrimp has a load of sensors on board to track the movement of the cattle - yet another potential use for robots being trialled by the guys at Sydney Uni.

SALAH SUKKARIEH: So what we're seeing is that there's greater interest from agriculture in general to use robotics in various forms. So, we've got some project funding now from Horticulture Australia to look at ground vehicles and how ground vehicles might be used in agriculture.

And so what you'll probably start to see is this process of sensing up platforms, maybe not using them for mustering or harvesting, but using them for understanding more about the farm - you know, where is the biomass, what's the soil properties like, where is the cattle now, what are the water levels like, what's the crop yield like?

PRUE ADAMS: A Japanese company best known for making motorbikes, Yamaha is the world's only major producer of agricultural UAVs.

OPERATOR: You use a UAV for what's traditionally called the three Ds: anything that's dirty, dull or dangerous. So, that really suits agricultural spraying down to the ground.

PRUE ADAMS: First developed in 1989, these units came about because of the high death and injury rate of chopper pilots aerial spraying Japanese rice crops. The worldwide head of Yamaha flew in to launch the RMAX, as they call it, near Picton in New South Wales. Hiroyuki Yanagi claims these machines are now used in around 60 per cent of Japan's rice paddies and he see real potential for weed control in Australia.

HIROYUKI YANAGI, PRESIDENT, YAMAHA MOTOR CO.: Today, 2,400 units of this machine are used for the Japanese rice production. And after that, the application has been developed towards the surveillance jobs, also monitoring jobs. That's the situation today. ... We developed the Korean market almost since 10 years ago and Korean rice production also using this machine very well. And actually, Australia is the third country of the market what we are targeting right now.

GREG HARRIS, WEED CONTROLLER: Been looking for a long time for something sort of a little bit outside the square in regards to weed control. Especially the terrain where we work in and around the ACT. It's quite hilly, gullies and stuff like that.

PRUE ADAMS: A weed control contractor, Greg Harris was the first person in Australia to legally use this rig. He's been through an extensive four-month training program and is now accredited with the Civil Aviation Safety Authority and the EPA. He must stick to a strict code of conduct, keeping the craft below 400 feet and operating always within line of sight.

GREG HARRIS: Being my age and never really playing PlayStation or any sort of video games whatsoever and then picking this up for the first time was more than a challenge.

PRUE ADAMS: If you're sitting at home thinking, "That looks like fun. I'd like to buy one of those," it's not that easy. This size and type of machine falls under international arms regulations. While it can be imported, it can't be sold to an individual, so Yamaha leases them to franchisees.

GREG HARRIS: You buy the franchise. Yamaha supply you with everything, and they train you. But you have to be a part of a franchise to be trained as well. It's very, very controlled through Yamaha Motors, and at this stage, the weed-spraying scenario is the only one that we can use, but they are looking at other capabilities for the machine. But it's a $120,000 machine, I'd rather lease it than buy it.

PRUE ADAMS: There are now two franchisees: Mr Harris and a Longreach environmental consultant, but the Japanese company plans to next year launch a unit with remote sensing and a camera and has set its sights on operating 50 RMAXs within three years.

Back in the almond orchard where we began this story, the air and ground assault continues.

The property owner, Tim Orr, hovers in the background, while the hexacopter takes moving footage of the tree canopy.

On foot, scientists are recording the blossom count with a camera and a notebook, while Shrimp, fitted with 3D lasers and multiple colour cameras, also drags a sensor along the ground to measure soil conductivity.

JAMES UNDERWOOD: Now we can relate that information back to the rest of the information we're getting from the robot and build up maps essentially, like, relating to the soil health, but also because we're using these cameras, we can also measure things like the yield on the trees, or at the moment we're in flowering season, so measuring the quantity of flowers on the different trees, correlate that to the properties of the soil and build this really rich source of information, this really rich picture that can be of use to farmers when they're managing their process.

TIM ORR, LAKE CULLULLERAINE ALMONDS: At the moment they're counting buds in flowers and they'll be back in a few months and scan the same areas to do a count on the actual nuts. And then at harvest, we will harvest the rows individually and weigh them so they have some more information to reference to.

PRUE ADAMS: And what benefit is it knowing what you're going to be harvesting in a few months' time?

TIM ORR: Knowing this early, it gives you a chance to adjust your nutrition program, and if you're going to be forward-selling any products, you know what you may have available for sale.

PRUE ADAMS: Australia leads the world in field robotics and our comparatively flexible aviation rules, combined with wide open spaces perfect for trials gives a lot of scope for agricultural robotic aviation.

ZHE XU: We're certainly hoping to see the robots become more autonomous, but there are significant research and engineering challenges that we have to overcome, as well as proving that there is an economic benefit to doing so and overcoming any legislative or legal issues that we come across.

SALAH SUKKARIEH: What we are seeing is over the next five years, most likely you'll start to see more and more robots on the farm and those robots are giving us more farm intelligence, just gathering information about the farm, processing that data and providing that information across to the grower or to the farmer.